It is the long-range goal of this project to study the co-oxygenation of xenobiotics by prostaglandin synthetase, particularly the pulmonary prostaglandin synthetase. The generation of toxic intermediates, carcinogens, mutagens, etc., during the co-oxygenation of benzopyrene during the metabolism of arachidonic acid by guinea pig lung and ram seminal vesicle microsomes. The involvement of cytochrome P-450 in this process is also under investigation.